Summarizing Applications of Atomic Excitations and De-excitations

Applications of Atomic Excitations and De-Excitations Summary

• An important atomic process is fluorescence, defined to be any process in which an atom or molecule is excited by absorbing a photon of a given energy and de-excited by emitting a photon of a lower energy.
• Some states live much longer than others and are termed metastable.
• Phosphorescence is the de-excitation of a metastable state.
• Lasers produce coherent single-wavelength EM radiation by stimulated emission, in which a metastable state is stimulated to decay.
• Lasing requires a population inversion, in which a majority of the atoms or molecules are in their metastable state.

Glossary

metastable

a state whose lifetime is an order of magnitude longer than the most short-lived states

atomic excitation

a state in which an atom or ion acquires the necessary energy to promote one or more of its electrons to electronic states higher in energy than their ground state

atomic de-excitation

process by which an atom transfers from an excited electronic state back to the ground state electronic configuration; often occurs by emission of a photon

laser

acronym for light amplification by stimulated emission of radiation

phosphorescence

the de-excitation of a metastable state

population inversion

the condition in which the majority of atoms in a sample are in a metastable state

stimulated emission

emission by atom or molecule in which an excited state is stimulated to decay, most readily caused by a photon of the same energy that is necessary to excite the state

hologram

means entire picture (from the Greek word holo, as in holistic), because the image produced is three dimensional

holography

the process of producing holograms

fluorescence

any process in which an atom or molecule, excited by a photon of a given energy, de-excites by emission of a lower-energy photon